by David Jackson, USA TODAY

by David Jackson, USA TODAY

These were some of the come-hither e-mail subject lines that President Obama's campaign team used to raise money -- and they worked.

"Most of the $690 million Obama raised online came from fundraising e-mails," reports Joshua Green in Bloomberg Businessweek.

And the subject lines were key.

"We did extensive A-B testing not just on the subject lines and the amount of money we would ask people for, but on the messages themselves and even the formatting," said Amelia Showalter, director of digital analytics for the campaign.

"The campaign would test multiple drafts and subject lines -- often as many as 18 variations -- before picking a winner to blast out to tens of millions of subscribers. 'When we saw something that really moved the dial, we would adopt it,' says Toby Fallsgraff, the campaign's e-mail director, who oversaw a staff of 20 writers.

"It quickly became clear that a casual tone was usually most effective. 'The subject lines that worked best were things you might see in your in-box from other people,' Fallsgraff says. 'Hey was probably the best one we had over the duration.'

"Another blockbuster in June simply read, 'I will be outspent.' According to testing data shared with Bloomberg Businessweek, that outperformed 17 other variants and raised more than $2.6 million."